Core catcher



Patented Mar. 28, 1939 PATENT OFFICE CORE OATCHER Carl Francis Baker, Taft, Calif.

Application April 25,

1936, Serial No. 76,476

Renewed December 30, 1938 Claims.

This invention relates to well drilling apparatus, and particularly pertains to a core barrel and catcher adapted to be used in conjunction with a conventional type of core drill.

In obtaining samples of formation from oil wells it is common practice to drill ahead of the normal drilled depth of the well to cut a cylindrical solid core. These cores are removed from `the well after having been cut by a circular cutter having a central opening to accommodate the core, and when removed give geologicalf information relative to the formation Which would be penetrated if the well bore is to continue to a greater depth. Various devices have been provided to catch the cut core and -to insure that when the core drill is removed from the well the sample would be properly extracted. These structures have in a great many instances been complicated and do not always operate positively. It is the principal object of the present invention therefor to provide a core catcher which may be positively drilled from Ithe top of the Well and which will act to engage the core and insure that it is extracted when the core catcher is withdrawn.

The present invention contemplates the provision of a tubular member within which a core may be caught, said member having means associated therewith for engaging the core at its lower end and holding the same while it is extracted, the operation of the device being effected by imposing uid pressure upon the corel catcher from the top of the well to actuate the core engaging elements and to hold them in actuated position until the core is recovered.v

The invention is illustrated by way of example in the accompanying drawing in which:

Figure 1 is a view in elevation showing the present invention as attached to a drill pipe with parts thereof broken away for the sake of convenience.

Fig. 2 is an enlarged View in longitudinal section showing the core catching device in its inoperative position.

Fig. 3 is an enlarged view in vertical section similar to Fig. 2 and showing the core catcher in its operative position.

Fig. 4 is a view inv transverse section' through the core catcher vas seen on the line l-l of Fig. 2. p f

Fig. 5 is a view in transverse section through the core catcher as seen on the line 5-5 of Fig. 2.

Fig. 6 is a view in transverse section through the core catcher as seen on the line 6 3 oi Fig. 3 and shows the core engaging elements in their set position. l Referring more particularly to the drawing, Ill indicates a drill stem at the lower end of which a core catcher II is secured, and beneath which (Cl. Z55-72) a core drill bit I2 is attached. The bit I2 may be of any desired construction to cut a cylindrical core from formation being penetrated. At the upper end of the drill string is a fitting I3 carrying a valve I 4 through which a valve ball may be introduced into the drill string and allowed to drop to the bottom of the well in a manner to be hereinafter described. The valve structure includes a rotatable valve I5 having an opening I6 therein through which the valve may pass and after which the valve may be closed to permit fluid pressure to be imposed upon a column of fluid within the drill string. It will be understood that suitable connections are provided at. the upper end of the tting I3 to establish communication with the drilling uid circulating pumps at the well and for the purpose of forcing fluid downwardly within the drill string to Aactuate the core catcher in a manner to be end of the housing is threaded at 2I to receivev a bottom closure structure 22 carrying a threaded sub 23 adapted to engage a tubular member 24 by which the core drill bit I2 is supported. The portion of the structure 22 above the sub 23 comprises a cylindrical wall 25 substantially the same diameter as the lower wall section 26 of the housing I1 and an end wall 21. VFluid circulating openings 28 are formed through the end wall 21 to make it possible for the drilling fluid of the well to circulate downwardly and outwardly into the well bore and thereafter upwardly to the top of thewell in the usual manner. The sub or threaded pin 23 is formed with a central passageway therethrough to accommodate the upwardly projecting end of the core being cut and to.permit this core to pass upwardly into the core barrel and catcher as core drilling progresses. Mounted in the end wall 21 of the structure 22 isa core guide sleeve 30 which has a central passageway 3| through it in longitudinal .alignment with the central passageway 29 through the pin 23. The core guide sleeve structure 30 includes a threaded base portion 32 adapted to be screwed into a threaded counterbore 33 provided in the end wall 21 of the sub 23 and above which a cylindrical portion 34 occurs having side passageways 35 therethrough to receive core cutting and retaining dogs 36 operating in a manner to be hereinafter described. 4Above the cylindrical portion 34 is a reduced cylindrical portion 31 through whichthe upper end of the passageway 3I occurs. The reduced cylindrical portion of the guide sleeve extendsthrough a cross head 38 which, as shown in Fig. 5, comprises a central circular portion 33 and radial arms 40. The radial arms 4U extend outwardly and terminate in arcuate end faces which conform to the inner circumference of the wall portion 26 of the main housing I1. 'Threaded into the wall 26 at diametrically opposite sides thereof are shear pins 4| having extensions 42 project into recesses formed in the ends of the radial arms 40 of the cross head 38. pins temporarily hold the cross head 38 in an inoperative and immovable position with relation to the housing structure I1. An inner core bar--4 rel 43 at its lower end is threaded into the central bore 44 of the cross head 38. The core guide sleeve extends into the lower end of the inner core barrel 43 and has a sliding flt -with relation thereto so that the innerlcore barrel may move downwardly over the upwardly extending core guide sleeve. The upper end of the inner core barrel 43 is fitted with a valve `ball seat 45 upon which a valve ball 46 rests. A perforated valve cage 41 is detachably mounted on the upper end ofthe core barrel 43 and above the valve seat 45 so that the valve ball 46 will be retained in the valve cage 41, and so that iluid may ow through the. perforations in the cage when the valve ball is unseated. The top of the valve cage terminates at a point slightly below'a uid inlet tube 48 which is fitted with packing rings 49 by which a tight ilt occurs between the tube 48 and the wall of the central bore I8 occurring within the upper end of the housing I1. The upper end of tube 48 is fitted with a nut 50 threaded thereon to Vhold the packing rings 49 in position. The nut 50 has a central tapered l opening leading downwardly and inwardly to form a seat for a valve ball 5I which may be dropped into the drill pipe through the valve I4 previously described.

Extending downwardly from the inlet tube 48 and telescoping over the inner core barrel 43 is an operating sleeve 52. The wall of sleeve 52 flares outwardly toward its lower end and rests against the upper face of the cross head 38. The diameter .of the lower openend of the operating sleeve 52 is materially greater than the diameter of the hub 33 of the cross head 38, so that fluid passageways 53 will occur around the cross head and permit the drilling fluid to flow outwardly through the passageways 28 in the bottom closure structure 22. Downward movement of the operating sleeve 56 is produced by the pressure of fluid forced downwardly through the drill pipe I0 and encountering the valve ball 5| after it hasbeen dropped upon its seat. Mounted upon the under face of the cross head 38 are the core cutting and retaining members 36 which are pivotedl thereto on pivot pins 54. The core cutters and retainers 36 are designed to be forced inwardly through openings 35 in the cylindrical portion 34 and to positively impinge against the opposite sides of a core 55.

The free edges of members 36 provide cutters which willv act to sever the core and hold the upper cut section of core so as to close the core barrel and to substantiallyinterrupt downward ilow of drilling fluid from the barrel.

The under faces of the retainers 36 are serrated as indicated at 56 and engage lock lugs 51 which are carried by the member 32 and tend to lock the members 36 in their core retaining posi- These Fig. 2 of the drawing, 'and the cross headv 38 is set in its temporarily locked position with the pins 42 holding it against movement. At this time the lower free ends of the core retaining members 36 extend into the openings 35 at opposite sides of the member 34. During the cutting of the corea circulation of drilling fluid. may be effected in the usual manner by forcing the fluid downwardly through the drill pipe I0 and the tube 48 into the operating sleeve 52, and then around the cross head 38 through the passageways 53, after which the fluid will pass outwardly through the openings 28 into the drill bore. The iiuid will then be free to circulate upwardly through the well in the usual manner. When a desired length of core has been cut by the core drill the core catcher may be operated. This is done by first dropping the valve ball 5I through the drill pipe until it rests within the seat at the upper end of the flow tube 48. This will obstruct downward ilow of drilling fluid through the flow tube and further force exerted by the drilling fluidl will move the tube 48 with its packing downwardly and cause the operating sleeve 52 to force against the cross head 38 and the pins 42 with sufiicient pressure to shear the pins 42 and to permit the cross head to be released for further downward movement. The downward movement of the cross head will act upon the pivot ends of the members 36 to force the free cutting ends of the members inwardly through the openings 35 and against the sides of the core 55. Ro-

tation of the drill stem and the core catcher.

structure will act, while the cutting members- 36 are urged inwardly to sever the core so that a length will be retained within the core barrel as the members 36 become locked by lugs 51. This will cause the core to be engaged and held. Attention is directed to the fact that as the tube 48 is forced downwardly by the pressure of the fluid acting against the ball 5I the upper end of the nut 56 will uncover .relief passageways 59 which-will allow the downwardly moving drilling fluid to pass out into the drill bore. This will be accompanied by a drop in pressure of the drilling uid and will indicate to the operator at the top of the well thatthe core catcher has been actuated to a degree where the members 35 have severed the core and are in a retaining position. Rotation of the device may then be discontinued. As the core retaining elements 36 are forced inwardly their serrations 56 on their outer sides will engage and lock with the lock lugs 51 previously described, and will thus insure that the retaining elements will be held in locked position until the entire structure has been removed from the well. Attention is directed to the fact that as the core moves upwardly within the core barrel 43 during operation of the device, such fluid as occurs within the core barrel 43 may be displaced and will ilow out at the upper end of the core barrel by lifting the valve ball 46 and passing through the perforations of the ball cage 41.

It will thus be seen that in the operation of the structure here disclosed a core barrel is provided which will positively sever -a core and hold thesame as controlled from the top of the well, and that furthermore positive information relative to the operation of the device may be ascertained at the top of the well due to variation in fluid pressure. It will further be evident that the core catcher here disclosed is simple in its construction and operation, and that it may operate positively at all timesand without any undue strain.

While I have shown the preferred form of my invention, as now'known to me, it 'will be understood that various changes might be made in the combination, construction, and arrangement of parts, by those skilled in the art, without departing from the spirit of the invention as claimed.

Having thus described my invention, what I claim and desire to secure by Letters Patent is: l. In combination with a core drill, a core catcher comprising an outer housing having a connection at its lower end for the core drill and a connection at its upper end for a drill string by which the structure is supported, means being provided to permit the flow of fluid from the drill string through the core catcher and into the well, core retaining means Within the housing, a. core barrel associated therewith and into which a core may be projected as it is cut, means permitting a circulation of iiuid upwardly. through the core barrel and preventing a down flow of fluid through the core barrel, a cross head Y slidable within the housing and carryingthe core barrel and core retaining means, an operating tube slidable within the housing and through which a circulation of drilling fluid may normally take place, a valve seat at the upper end of the operating tube and carried thereby, means creating a fluid seal between the bore of the housing and the upper end of said operating tube whereby the flow of fluid around the tube will be prevented, and a valve member adapted to be dropped through the drill string to rest upon the valve seat and. prevent circulation of drilling iiuid whereby the downward pressure of said fluid will move the operating tube and the cross head to actuate the core retaining means.

2. In combination with a core drill, a core catcher comprising an outer housing having a connection at its lower end forthe core drill and a connection at its upper end for a drill string by which the structure is supported, means being provided to permit the now of fluid from the drill string through the core catcher and into the well, core retaining means within the housing, a core barrel associated therewith and into which a core may be projected as it is cut, means permitting a circulation of uid upwardly through the core barrel and preventing a down ow of fluid through the core barrel, a cross head slidable within the housing and carrying the the core barrel and core retaining means, an operating tube slidable within the housing and through which a circulation of drilling iiuid may normally take place, a valve seatat the upper end of the operating tube and carried thereby,

means creating a uid seal between the bore of the housing and the upper end of said operating tube whereby the flow of iluid around the tube will be prevented, a valve member adapted to be dropped through the drill string to rest upon the valve seat and prevent circulation of drilling fluid whereby the downward pressure of said iiuid will move the operating tube and the cross head to actuate the core retaining means, and means temporarily holding the cross head against movement until said valve ball has been dropped upon its seat and iiuid pressure. has been imposed thereon.

3. In combination with a core drill, a core catcher comprising an outer housing having a connection at its lower end for the core drill and a connection at its upper endv i'or a drill string by which the structure is supported, means being provided to permit the flow of iiuid from the drill string through the core catcher and into the well.

core retaining means within the housing, a core of the core barrel.

` able within the housing and carrying the core barrel andcore retaining means, an operating 'tube s1idab1e within the housing and through which a circulation of drilling uid may normally take place, a valve seat on the upper end of the operating tube and carried thereby, means creating a fluid seal between the bore of the housing and the upper end of said operating tube whereby the flow of fluid around the tube will be prevented, a valve member adapted to be dropped through the drill string to rest upon the valve seat and prevent circulation of drilling uid whereby the downward pressure of said fluid will move the operating tube and the cross head to actuate the core retaining means, means temporarily holding the crossghead against movement until said valve ball has been dropped upon its seat and iiuid pressure has been imposed thereon, and means engaging with the core retaining means to temporarily lock them in their gripu Ding positions.

4. In combination with a core drill, a core catcher comprising an outer housing having a connection at its lower end for the core drill and a connection at its upper end for a drill string by which the structure is supported, means being provided to permit the ow of iiuid from the drill string through the core catcher and Ainto the well, core retaining means within the housing, a core barrel associated therewith and into which a core may--be projected as it is cut, means permitting a circulation of fluid upwardly through the core barrel and preventing a down flow of iiuid through the core barrel, a cross head slidable within the housing and carrying the core barrel and core retaining means, an operating tube slidable within the housing and through which a circulation of drilling uid may normally take place, a valve seat at the upper end of the operating tube and carried thereby, means creating a uid seal between the bore of the housing and the upper end of said operating tube whereby the iiow of fluid around the tube will be prevented, a valve member adapted to be dropped through the drill string to rest upon the valve seat and prevent circulation of drilling fluid whereby the downward pressure of said uid will move the operating tube and the cross head to actuate the core retaining means, means temporarily holding the cross head against vmovement until said valve ball has been dropped upon its seat and fluid pressure has been imposed thereon, and uid circulating ports adjacent the upper end of the housing, said passageways being closed normally by the packing on the operating tube and establishing communicationfrom the drill string to the well when the 'operating tube has been moved to actuate the retaining elements.

5. In combination with a core drill, a core catcher, comprising an outer housing having a connection at its lower end for said core drill, and a connection at its upper end for a drill string by which the structure is supported, circulation of fluid from the drill string through the core catcher into the well and through the structure being permitted, and core retaining means within the housing to substantially close the lower end CARL FRANCIS BAKER. 

